Curling irons are often designed for specific voltages, either that normally found in the United States (about 120 volts a.c.) or that found in many European countries (about 240 volts a.c.). If, then, the curling iron is used in a country for which it has not been designed, an auxiliary transformer is used to adjust the voltage. If a transformer is not used, the unit will produce different temperatures with the different voltages, or may even burn out. Compensating circuits, such as voltage dividers have proven either cumbersome or expensive.